Sustainable Land Development Today - January 2008 - (Page 42) By Vaikko Allen Industry Spotlight ment chosen as they are of hasty or uninformed design. Proper application of LID principles requires a similarly site-spe- Installed StormFilter system. Inclusion of the system maxcific approach. It requires an imized developable land, and allowed developers to meet assessment of predevelopment low impact development goals. hydrology and seeks to maintain that hydrology during and after con- desire to integrate commercial, residenstruction through optimum IMP (inte- tial and transportation elements in a grated management practice) selection. density that encourages car-less travel. However, application of the practices Use of the manufactured filters also prowithout the principles leads us back to vides a reservoir for pollutants where the “black box” method of design. Just they are out of human or animal contact as blanket approvals of manufactured and do not affect the aesthetics of the BMPs can short circuit the design development. An inspection and mainprocess, blanket endorsement of IMPs tenance contract between the site manager and the filter manufacturer has can have the same effect. been in place since installation in 1999. Since that time, the systems have been ORENCO STATION cleaned every one to two years and HILLSBORO, Ore. approximately 30 yards of material have Efficient use of land space, which may been recovered not including the spent be enabled by the use of innovative non- filter media. The footprint of a landLID techniques, can also shrink the foot- scape-based treatment system that print of development and encourage would be able to assimilate or store this multi-use development typical of new load of pollutants in an innocuous way urban designs. A good example is Orenco would undoubtedly be massive. Station in Hillsboro, OR. This 190 acre site was redeveloped in 1997 with a focus on Choosing the Right Solution providing light rail and pedestrian comThe most suitable stormwater manmuting options for its 2,600 residents. agement system designs are often a The site incorporates many features combination of approaches that take familiar to LID practitioners like shared into account local economic, political driveways, sidewalks with adjacent and environmental concerns. These planter strips and narrow streets. It also designs are encouraged by clear perrelies on three underground stormwater formance standards and allowance for filtration systems from CONTECH flexibility to use innovative approaches Stormwater Solutions. The Stormwater to meet them. The LID movement is an Management StormFilter can treat a comimportant part of the solution for most bined 4.7 cfs of runoff to meet the treatsites, but it is not a universal remedy. ment goals set by the City of Hillsboro. Efforts to require elements of LID on all Exclusive use of land based treatsites may unnecessarily stifle the other ment systems was not feasible on this options that are more suitable. SLDT site due to high land values and the Developing LOW IMPACT Stormwater Management Solutions Low Impact Development (LID) has quickly emerged as an important stormwater management design strategy. The core goal of an LID-based design strategy is simple; design sites to have minimal impact on the natural hydrologic balance so that the structural and water quality impacts of development are minimized downstream. LID implementation however is less straightforward. In some cases a regulators stated preference for LID, as opposed to a conventional “end-ofpipe” design, is interpreted as a requirement that only landscape based best management practices (BMPs) should be used for stormwater management. Stormwater management system design is not a one size fits all process. On urban sites, the most effective and economical solution is likely to be a combination of hydrology-centered planning, educational strategies, landscape-based BMPs, and innovative manufactured solutions. Manufactured bmps vs. LID – A Misguided Distinction As developers, it important to ensure your design engineers are including stormwater management systems that are tailored to the individual demands of your site – selecting systems that are truly “low impact” and help you maximize your investment. One of the criticisms of manufactured options is that they are too often designed as a “black box” with unknown sizing processes, unproven performance and inadequate maintenance after installation. These criticisms are valid in many cases, but are not so much symptomatic of the type of treat- 42 January 2008 Sustainable Land Development Today
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